METHOD AND APPARATUS FOR MANUFACTURING FOOT PADS ON THE SITE WITH SELECTIVE FOAM DISTRIBUTION
BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for manufacturing foam pads in situ having a foaming composition contained within a flexible bag formed of polymer film provided as continuous woven material, the polymer film it is sealed along the longitudinal and transverse seals to contain the foaming composition, and is cut to separate a foam pad in situ from the rest of the woven material. On-site foam packaging is a very useful technique for protecting packaged objects on request. In its most basic form, the foam on-site packaging comprises injecting a foaming composition from a dispenser into a container containing an object to be padded. Normally, the object is wrapped in plastic to protect it from direct contact with the growing (expanding) foam. As the foam grows, it expands into the empty space between the object and its container (ie, a corrugated cardboard box), which forms a custom pad for the object. A common foam composition is formed by mixing
an isocyanate compound with a hydroxyl-containing material, such as a polyol (ie, a compound containing multiple hydroxyl groups), usually in the presence of water and a catalyst. The isocyanate and polyol precursors react to form polyurethane. At the same time, the water reacts with the isocyanate compound to produce carbon dioxide. The carbon dioxide causes the polyurethane to expand into a foamed cellular structure, i.e., a polyurethane foam, which serves to protect the packaged object. In other types of on-site foam packaging, an automated apparatus produces foam pads on-site by making bags of flexible plastic film and by providing a foaming composition in the bags as they are formed. As the composition expands into a foam within a bag, the bag is sealed and normally poured into a container containing the object to be padded. Again, the growing foam tends to expand in the available space, but it does so within the bag. Since the bags are made of flexible plastic, they form individual foam pads to fit around the packed objects. Exemplary types of such packaging apparatuses are assigned to the assignee of the present application, and are illustrated, for example, in the North American Patents
Nos. 4,800,708, 4,854,109, 5,027,583, 5,376,219 and 6,003,288, the contents of which are hereby incorporated herein by reference. As can be seen from the patents listed above, the typical method for forming a foam pad in situ from a plastic bag is to thermally seal and seal layers of plastic film material, both transverse and longitudinally, according to they are supplied by a reserve supply to form a generally rectangular bag with the foam inside. In some cases, the reserve supply of the plastic film material may comprise a C-folded fabric, so that one side of the bag is more a fold than a thermal seal. Foam-in-place packaging devices that operate according to these methods have gained wide and rapid acceptance in the market and have successfully fulfilled their purposes. However, we continuously seek to improve the operation of these devices. In this regard, a difficulty associated with on-site foam pads manufactured in a conventional manner is that the pad, as discharged from the apparatus, does not have the foaming composition evenly distributed in the pad. The foaming composition tends to be dispensed to the bottom of the bag and immediately begins to expand to
as the chemical precursors react. It is common practice for an operator to take the pad unloaded from the apparatus, place the pad on a flat surface and use his hands to redistribute the foam forming composition within the pad in a layer of generally uniform thickness before the pad is placed in a shipping container. The problem with this technique is that, by the time the operator can place the pad on a flat surface, the foaming composition has already experienced a considerable degree of expansion. When the already formed foam is redistributed, the cellular structure of the foam is affected. This can cause the pad to increase its volume to a lesser degree than it was designed for and, therefore, the density of the foam is higher than desired. In addition, the uniformity of the density of the foam can be compromised, to the extent of creating considerable irregularities in the density of the pad. As a result, the pad may not have the protective properties it was designed to have.
BRIEF COMPENDI OF THE INVENTION The present invention meets the needs described above and achieves other advantages. In
One embodiment of the invention provides a method for manufacturing foam pads in situ, wherein a pads production cycle comprises the following steps: providing a pair of continuous polymer film portions extended along a longitudinal direction and placing the film portions in opposite relation parallel to each other; placing a foam dispenser between the film portions to deliver a foaming composition between the film portions, so that the foaming composition can react to form an expanded polymer foam material, which the dispenser can control to present an "on" state, wherein the foaming composition is dispensed by the dispensing device or in a "deactivated" state, where the supply of foaming composition is stopped and; placing the foaming composition selectively between the film portions by performing at least one of the following operations: (1) moving the dispensing device along a transverse direction of the film portions as the foaming composition is being dispatched; and (2) advancing the film portions in the longitudinal direction through a dispersion device
structured and designed to apply pressure on certain areas of the film portions together, to cause the foaming composition to be redistributed while the foaming composition is in a less than fully expanded state. The dispersing device can redistribute the foaming composition in various ways to achieve various effects. In one embodiment, the dispersion device redistributes the composition in a layer of substantially uniform thickness. In another embodiment, the dispersion device redistributes the composition in a layer whose thickness varies in a predetermined manner in at least one of the longitudinal and transverse directions. The redistribution or dispersion of the foaming composition by the dispersion device occurs immediately after the foaming composition is dispensed. Accordingly, the composition does not have time to experience any considerable degree of foaming and, therefore, the redistribution of the composition does not alter the structure of the foam that forms at the end. The composition can be expanded to the desired degree so that the pad has the desired protective properties. In yet another embodiment, the foam forming composition is dispensed as a plurality of discrete volumes
of foam forming composition spaced in at least one of the transverse and longitudinal directions. The invention also provides an apparatus for manufacturing foam pads in situ. According to one embodiment of the invention, the apparatus comprises: a guide and film delivery system for providing a pair of continuous polymer film portions extended along a longitudinal direction and for placing the film portions in opposite parallel relation each; a dispenser disposed between the film portions and operable to deliver a foaming composition between the film portions, so that the foaming composition can react to form an expanded polymer foam material. a structured film driving mechanism and designed to advance the film portions in the longitudinal direction; and a structured dispersion device and designed to apply pressure in predetermined areas of the film portions advanced to each other, to cause the foaming composition to be redistributed while the foaming composition is in a less than fully expanded state. . According to one of the modalities of the
invention, the dispersing device comprises the first and second film clutch members, between which a space is defined where the forward film portions pass with the foaming composition therebetween. A width of the space is adjustable by moving the first and second film clutch members in relation to each other. In one embodiment, the first film clutch member comprises a drive roller rotated by a drive motor about an axis parallel to the transverse direction, and the second film clutch member comprises a dispersion member extending as far as possible. Along a parallel axis a and spaced from the axis of the control roller, the control roller contacts one of the film portions and the dispersion member contacts the other portion of the film. The dispersing member may be a free-rotating control roller, a non-rotating control roller, connecting rod or bar, or the like. The film portions are advanced in the longitudinal direction by the control roller, which forms lines of contact with a pair of transversely spaced driven rollers, the opposite longitudinal edges of the film portions pass through the contact lines and are clutched by friction and advanced by the control roller. The width of the space between the control roller and the dispersion member can be established as a function
of a characteristic of the pad that you want to produce. For example, the width can be established as a function of the foam composition volume dispensed. It is also possible to vary the width of the space as the film portions are advanced through the space. For example, the space can be progressively widened as the film portions are advanced, to justify the expansion of the foaming composition. As another example, the space may be varied to cause predetermined variations in thickness of the foaming composition layer along the longitudinal direction. In one embodiment, the dispersion member is mounted on a frame that rotates about a pivot spaced from and parallel to the axis of the dispersion member, so that rotation of the frame around the pivot causes the space between the dispersing member and the control roller varies in width. According to one aspect of the method of the invention, at the beginning of a pad manufacturing cycle in situ, the frame is initially positioned in such a way that the dispersion member is in a closely adjacent first position (i.e., tightly engaged with ) the control roller and the foaming composition is dispensed between the film portions upstream of the dispersion member and roller
of command. Then, the frame is rotated to move the dispersion member to a second position spaced farther from the control roller, to locate the space between them and the control roller is rotated to advance the film portions through the space . According to one embodiment of the invention, the control roller advances a section of the film portions through the space and then stops to interrupt the film portions and the film portions are sealed along a transverse seal and they cut. The sealing and cutting steps can be performed simultaneously by a hot member placed in contact with the film potions. In one embodiment, a pressure member is mounted on a frame and the frame is rotated about the pivot to cause the pressing member to press the portions of film against the hot member, in order to seal and cut the film portions. At the beginning of a pad manufacturing cycle, a transverse seal of the film portions can be positioned downstream of the dispersing member and control roller and the dispersing member can be placed in close clutch with the control roller to press the portions of film against the control roller. Consequently, when the training composition of
foam is dispensed between the film portions, the transverse seal is initially isolated from the foaming composition by the narrow clutch between the dispersion member and control roller. The incidence of breaking the transverse seal by forced dispensing of the foaming composition is, therefore, considerably reduced or eliminated. The invention allows the controlled and selective placement of foam in a pad by controlling variables such as movement of the foam dispenser, speed of movement of the dispenser, advancement of the film portions, film overtaking speed, "on" and "on" operation. off "of the dispenser, and operation of the dispersion member to control the foam thickness.
BRIEF DESCRIPTION OF THE VARIOUS VIEWS OF THE DRAWINGS Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale and where: FIGURE 1 is a perspective view of an apparatus for manufacturing foam pads in a bag according to an embodiment of the invention; FIGURE 2 is a cross-sectional view
Schematic through the apparatus along a plane orthogonal to the axis of the polymer film supply roll; FIGURE 3 is a front elevation of the apparatus showing details of the mechanism for traversing the foam dispenser; FIGURE 4 is a schematic illustration of a pad showing a possible pattern in which the foaming composition is dispensed according to one embodiment of the invention; FIGURE 5a is a schematic illustration of a pad after passing through a dispersion device, according to one embodiment of the invention; FIGURE 5b is a cross-sectional view through the pad of FIGURE 5a; FIGURE 6 is a schematic perspective view of a portion of an apparatus according to another embodiment of the invention; with an alternative film and drive supply system; FIGURE 7 is a top view of the film supply and drive system of the apparatus of FIGURE 6; Figure 8 is a side view of the film supply and drive system; FIGURE 9 is a schematic side view of the
film delivery system with the dispersion device and cross sealing and cutting devices, showing a foam formation composition being dispensed at the beginning of a cycle of manufacturing pads; FIGURE 10 is a view similar to FIGURE 9, at a later time in time at which the film drive system operates to drive the film and the dispersion device has been activated to establish the predetermined space between the dispersion and the control roller for redistributing the foaming composition between the film portions; FIGURE 11 is a view similar to FIGURES 9 and 10, at a later time in time at which the transverse and cutting sealing device has been activated to seal and cut the pad; FIGURE 12 is a front elevation of an apparatus with a foam dispenser mounted on a pivot according to another embodiment of the invention, showing the foam dispenser in a first position; FIGURE 13 is a view similar to FIGURE 12, showing the foam dispenser in a second position; FIGURE 14 illustrates a dispersion roll with a non-constant cross-sectional shape along its length;
FIGURE 15 is a schematic plan view of a pad formed using the dispersion roller of FIGURE 14; FIGURE 16 is a cross-sectional view along the pad of FIGURE 15; FIGURE 17 illustrates a generally U-shaped structured portion formed by folding the pad of FIGURE 15; FIGURE 18 is an exploded perspective view of an apparatus with a dispersion roller by actuation in accordance with a later embodiment of the invention; and FIGURE 19 is an exploded perspective view of the apparatus at an enlarged scale, showing details of the driving arrangement for directing the dispersion roller.
DETAILED DESCRIPTION OF THE INVENTION Next, the present invention will be described more fully with reference to the accompanying drawings in which some but not all embodiments of the inventions are shown. Certainly, these inventions may present modalities in various forms and should not be construed as limited to the modalities set forth herein; instead, these inventions are provided
so that this description complies with the applicable legal requirements. Similar numbers refer to similar elements completely. FIGURES 1 to 3 represent an apparatus 20 for manufacturing foam pads in a bag according to an embodiment of the invention. The apparatus includes a pair of parallel spaced frame members 22, 24, each of which is generally in the form of a plate and a plurality of support rods 26, or the like, which connect between the frame members 22, 24 to form a generally rigid frame. At the upper end of the frame, a pair of freewheeling tensioning rollers 28, 30 are rotatably supported between the frame members 22, 24 to support a supply roll 32 of two layer film material. The supply roll comprises two separate polymer layers placed one above the other and then wound around an empty tubular core to form a roll of the two-layer film material. As shown in FIGURE 2, a layer 34 of the two-layer film material is unwound from the supply roll 32 and advanced in a downstream direction in front of the tensioner roll 28; the layer 34 can be guided by two of the rods 26 as shown, or alternatively the upper rod 26 shown in FIGURE 2 can be omitted. The other layer 36 of the two layer film material is unrolled from the
supply roll 32 and through a contact line between the roll 32 and the other tensioner roller 30 and then advance downstream and is guided by another connecting rod 26. An apparatus of generally the same type for making foam pads in a bag using a two-layer film supply is described in US Patent No. 6,178,725 and US Patent No. 6,472,638, the entire disclosure of which is incorporated herein in its entirety. for reference. The apparatus includes a drive roller 40 which is mounted between the frame members 22, 24 near a lower end of the frame and is driven by a motor 42 mounted on the frame member 24. The apparatus further includes a pair of transversely spaced freewheeling rollers 44, 46 mounted on a shaft 48 extending between the frame members 22, 24. The drive rollers 44, 46 form lines of contact with the drive roller 40. The film layers 34, 36 slide across contact lines between the drive rollers and the drive roller, as shown in FIGURE 2. The drive roller 40 includes an elastically compressible outer surface and frictionally engages the film, in such a way that the film is operated considerably by the control roller without slipping. For example, the control roller can be formed by a
rigid cylindrical roller covered with a foam material coating such as silicone foam with a hardness of 70 Shore A durometer and a thickness of approximately 0.635 cm (0.25 inches). As illustrated, the drive rollers 44, 46 may have circumferential ridges that are spaced along the direction of the rollers to create longitudinal ridges at the edges of the film layers, which gives rigidity to the edges of the film and also helps to ensure that the film is driven directly out of the rollers and is not wound around the control roller 40. The apparatus further comprises a foam dispenser 50 which is mounted on a transport mechanism 52 located between the two film layers 34, 36. The transport mechanism 52 is slidably mounted on a guide rail 54 extending between the frame members 22, 24. A rotating feed screw 56 is rotatably mounted between the frame members and driven by a reversible motor 57. The feed screw engages a nut (not shown) in the transport mechanism 52. Thus, rotation of the feed screw 56 in one direction causes the transport system 52 and the dispenser 50 to move to the left along a guide rail 54 in FIGURE 3, and that the rotation of the feed screw in FIG. the direction
opposite moves the transport mechanism and the dispenser to the right in FIGURE 3. The variation in the rotational speed of the screw 56 causes the speed of movement of the dispenser to vary. The foam dispenser is fed by feed hoses 58, 60 which feed two precursor chemicals to the dispenser, where the precursor chemicals are mixed (either internally within a dispenser mixing chamber, or externally when dispensing from the dispenser), to form a foam forming composition. The composition is dispensed between the two layers 34, 46 of the polymer film material at a site just above (upstream of) the drive roller 40 and drive rollers 44, 46. By controlling the movement (i.e., positioning and, optionally, speed) of the dispenser 50 in the transverse direction it is possible to dispatch the foaming composition in any of several patterns. The possible patterns are further multiplied by driving the film layers 34, 36, while the composition is dispensed (and, optionally, by varying the movement speed of the film) and / or momentarily interrupting the flow of the composition one or more times during the travel of the dispenser 50 and / or during the movement of the film layers. FIGURE 4 shows only one of many possible patterns of foaming composition 62
which are possible according to the invention. The illustrated zigzag pattern is formed by the displacement of the dispenser from back to front, so that the dispenser changes directions three times while the film layers 34, 36 are driven by the control roller 40. The pattern is continuous because the composition forms an uninterrupted series. However, discontinuous patterns (not shown) formed by discrete discrete composition regions are also possible by momentarily interrupting the flow of the composition, as observed. For example, the foam can be dispensed as two or more bands extending transversely and longitudinally apart, as separate points transverse and longitudinally, etc. An alternative embodiment of a film and drive supply system according to the invention is shown in FIGS. 6 to 8. This embodiment employs a film supply roll 32 ', of C-folded film, for example, a film. flat along a longitudinal median line such that one edge of the flat film is aligned with the other edge of the flat film, thereby forming two portions 34 'and 36' of film in parallel overlapping relationship. The supply roll 32 'is mounted on a shaft 33 whose opposite ends protrude beyond the ends of the roll and engage the slots 35 in the frame members 22', 24 'which are configured
to cause the roll to clutch the control roller 40. The slots 35 are inclined in such a way that gravity drives the supply roll against the control roller. Accordingly, the rotation of the control roller causes the supply roll to rotate to release the film at C. The film is guided upstream and on a freewheeling guide roller 37 mounted between the frame members 22 ', 24' and the two layers 34 ', 36' are separated by a spacer member 39 to make room for the dispenser projecting between the layers of the open edge of the C-folded film. The film then slides through the contact lines between the control roller 40 and the drive rollers 44, 46, as in the previous embodiment. In the C-folded film embodiment of the apparatus, as best shown in FIGURE 7, the apparatus includes a longitudinal sealing device for sealing the two film layers 34 ', 36' together along the open edge of the film folded in C after the foaming composition has been dispensed between the layers. Various types of longitudinal sealing devices can be used, the invention is not limited in this respect. An appropriate type of longitudinal sealing device is a sealing wire such as that described in US Patent No. 6,550,229, which
contents are incorporated herein in their entirety for reference. This type of sealing device comprises a sealing wire 64 which is partially wrapped around the drive roller 44 and resides in a notch formed in the roller (i.e., between two of the previously mentioned circumferential flanges of the roller), so that the film layers pass through the contact line between the roller and the control roller 40, the sealing wire contacts the film layers. The sealing cable comprises a resistance wire that becomes hot with the passage of an electric current through the cable, to heat the layers of film to its melting point in the region located in contact with the sealing wire, sealing and joining together the layers. On the other hand, the sealing device may be as described in US Patent No. 6,472,638, the full disclosure of which is incorporated herein by reference. It will be recognized that in the first embodiment of the apparatus described above that employs a roll of two-layer film supply 32, such as a longitudinal sealing device is required for each of the edges of the film. Accordingly, a sealing device as described above may be associated with the other drive roller 46.
The following description of a dispersion device and a transverse and cutting sealing device is applicable to both of the embodiments of the invention described above. FIGURES 9 to 11 schematically illustrate the structure and operation of the dispersion device and the transverse and cutting sealing device according to one embodiment of the invention. The apparatus includes a dispersion member 7 0 movably mounted with respect to the control roller 40 and extends in parallel to the axis of rotation of the control roller. In the illustrated embodiment, the dispersion member 7 0 comprises a freewheeling roller which is mounted on a frame 72; however, on the other hand, the dispersing member may be a non-rotating member such as a connecting rod or the like, or it may be a driving roller that is rotatably driven by a suitable driving arrangement (not shown). The frame 72 itself is rotatably mounted on the apparatus such that it rotates about the shaft 48 of the drive rollers 44, 46. A reversible motor 74 (FIGURE 1) is coupled to the frame 72 to rotate the frame in one direction or the other. The rotation of the frame 72 around the axis of the shaft 48 causes the dispersion member 7 0 to move towards or away from the control roller 40. An encoder (not shown) may be associated with the frame 72 (for example, the encoder may be constructed
in the motor 74) to allow the rotational orientation of the frame to be detected and controlled by properly controlling the motor 74 located at the output of the encoder. FIGURE 9 represents the frame 72 in a position that places the dispersion member 7 0 in a narrow clutch with the control roller 40. The rotation of the frame 72 in one direction is effective to move the dispersion member away from the drive roller to create a space 74 therebetween, as shown in FIGURE 10. The control of the positioning of the frame 72 is effective to adjust the space 74 at any of the various distances depending on the requirements of the particular pad that is produced. Because the frame 72 rotates about the axis of the drive rollers 44, 46, the drive rollers remain in close clutch with the drive roller 40, regardless of the rotational position of the frame 72. According to the invention, the frame 72 can be initially positioned as shown in FIGURE 9, with the dispersing member 7 0 in close engagement with the control roller 40. The foam dispenser 50 is operated to dispense the foaming composition 62 between the film layers 34, 36. The frame 72 is rotated to move the dispersion member 7 0 away from the control roller 40 to establish a predetermined space 74 and the
the control roller 40 is rotated to direct the film through the apparatus, as shown in FIGURE 10. The dispersion member 70 presses the film portion 34 towards the opposite film portion 36 to make the composition 62 The foam formation is redistributed spaced between the film layers in a desired manner while the film is driven by the control roller 40. This redistribution of the composition advantageously occurs before the composition has experienced any degree of considerable expansion. The manner in which the composition is redistributed is dictated by the size of the space 74 and the configuration of the dispersion member 70, as well as whether the dispersion device rotates or is stationary. For example, FIGS. 5a and 5b show a pad processed by a constant circular cylindrical cross-section dispersion member, wherein the size of the space 74 is varied as the film is driven through the space. More particularly, the foaming composition is redistributed to include a region of relatively small thickness 76 caused by the reduction of space, flanked by two regions of greater thickness 78 created by the widening of the space 74. Thus, initially, according to the foam is dispensed and the film portions advance, the space 74 widens to produce one of the regions 78
thick, then the space is reduced to produce the thin region 76 and, finally, the space is enlarged to produce the second thick region 78. It is also possible to produce regions of different thickness by configuring the dispersion device in order to have a non-constant shape to redistribute the composition in a non-constant manner in the direction of the width or length of the pad. The asymmetric shape of the regions 76, 78, as depicted in FIGURE 5a, can be produced by dispensing the foam in a generally C-shaped configuration by running the dispenser back and forth and possibly varying the speed of the film. On the other hand, a generally symmetric shape can be produced by keeping the dispenser stationary while the foam is dispensed and the film is advanced. Once the film layers have been driven by a corresponding extension the desired extension of the pad to be protected, the control roller 40 stops and the frame 72 is rotated as shown in FIGURE 11 to make an anvil The sealant connected to the frame drives the film layers against a transverse sealing wire 82 which is heated by passing an electric current through the cable. The control roller 40 forms a backing member for the sealing wire 82, so that the anvil 80 can drive
firmly film layers against the sealing wire The anvil may have a surface that is elastically deformable. For example, the surface of the anvil may be formed by a layer of polymer foam such as silicone foam approximately 0.635 cm (0.25 inches) thick. The heated sealing wire simultaneously cuts the film layers and also seals the layers together to form a transverse seal that seals the complete pad along with its upper transverse edge and also cuts to create the transverse seal 83 of the bottom (FIGURE 9) so that the next pad occurs. FIGURES 12 and 13 represent an apparatus according to yet another embodiment of the invention, wherein parts of the apparatus have been omitted for clarity. The apparatus differs from the previously described embodiment in that the foam dispenser 150 is mounted on a transverse mechanism 160 that moves as a pivot rather than linearly translatable. More specifically, the dispenser is mounted on the lower end of an arm 162 that pivots about an axis 164 located at an intermediate position along the extension of the arm. The upper end of the arm 162 is connected to a connecting rod 166 of a fluid cylinder 168 such as a pneumatic or hydraulic cylinder. Therefore, the retraction of the connecting rod (FIGURE 12) pivots the arm 162 in one direction and the extension of the
connecting rod (FIGURE 13) pivots the arm in the other direction. By properly controlling the cylinder 168 as the foam composition is dispensed from the dispenser 150, the foam composition can be dispensed in various patterns, as described above. In accordance with any other of the embodiments of the invention, the apparatus may include various sensors to detect conditions in the apparatus and assist in the control of the operation of the apparatus. For example, it may be desired to manufacture a pad of a predetermined length. To control the apparatus for manufacturing the desired pad length, the supply roll may have opaque bars B printed along the film in a known fixed range, as shown in FIGURE 7. A photoelectric sensor (not shown) it can be located inside the box of the machine and directed to detect the bars. This sensor can differentiate the bars of the film without printing. The electronic control assembly (not shown) can count the bars based on the information received from the sensor and measure the length of film that has advanced. In this way, the controller can feed film accurately to make a pad of the desired length. This can also detect when the film supply runs out and thus can stop the machine so that it does not manufacture a pad
without a movie Alternatively, the rotation of the control roller 40 can be detected with an encoder or the like and the output of the encoder can be used to accurately determine how much stretch of film has been driven through the apparatus. The encoder can be built in the motor 42 or it can be separated from the motor. This allows the B-bars to be removed from the film roll. When starting the device, the controller performs a cleaning cycle for the solvent system of the dispenser and performs other self-tests. The solvent system can be described as in US Patent No. 6,811,059 entitled "Self-Cleaning of the Fluid Dispenser", the entire description is incorporated herein by reference. Before the apparatus manufactures the first pad, it starts a cycle with only film and without chemicals. This is to ensure that there is a transverse seal on the bottom 83 (FIGURE 9). The device produces an empty pad every time it is started, whenever the roll of film is changed or after any error condition. The operator then selects a length and thickness of pad by pressing keys on a keyboard connected to the controller. The length of the pad can have a few inches, up to many
feet, but most pads will have an average of 0.61 to 1.524 meters (1 to 5 feet). The thickness varies from approximately 3.81 to 5.08 cm (one and a half inches to 2 inches) after the foam has expanded. At the beginning of the cycle, the dispersion member 70 may be in the initial position, as shown in FIGURE 9. Dispatcher 50, 150 moves to a predetermined starting position and begins to dispatch. The control roller 40 starts to actuate the film and the space 74 between the dispersion member 70 and the control roller opens to the desired value, as indicated in FIGURE 10. The control roller advances the film, the correct amount of selected length. During actuation and dispatch, the dispenser can be traversed along the transverse direction (e.g., in a backward and forward motion), by spreading a bubble of foam within the film layers at the splice of the dispersion device and control roller. In addition, if desired, the dispersion member 70 can be moved to vary the size of the space 74 as the film advances. The quantity of chemicals dispensed is determined by the controller from the selected length and thickness of the pad. As the film is advancing, the longitudinal sealing device (s) can be operated to seal the film layers together
long or longitudinal edges. The sealing device can be momentarily reverted in one or more positions along the edge to create one or more spaces where the film does not fuse, thus allowing the air in the bag to be ventilated while the foam is extended. At the end of the driving cycle, the frame 72 is rotated in the transverse sealing position and cut and the pad is sealed and cut, as in FIGURE 11. The frame 72 is then rotated to a neutral position and the operator Take the expanding pad of the device. At the end of the cycle, the dispatcher is returned to a predetermined position. The apparatus may also include a sensor to determine if the dispenser injector is dirty and requires attention. Normally, when the injector of the dispenser is dirty, a cluster of foam will form at the end of the injector and will protrude below the injector. The apparatus may include a sensor such as a laser sensor positioned to direct a beam along a path that will be cleared as long as the injector does not have any significant foam clumps, but which will be blocked if the foam accumulates to some extent in the injector. The sensor and reflector may be located at predetermined locations, such as the end of one side of the scope range of the dispenser, out of the path of the
film through the device. Consequently, when the dispenser moves in the predetermined position, if the injector is not dirty, the laser beam is inversely reflected by a reflector to a detector, which indicates a normal condition of the injector. However, if the foam accumulates enough to block the beam, the detector does not receive the beam and thus indicates that the injector requires attention. Other types of sensors can be used instead of the laser and reflector array. According to the invention, the dispersion of the foaming composition is controlled as the foam is delivered between the layers and / or immediately after dispatch. Any manipulation of foam placement is complete when the chemical is in the liquid state prior to any degree of significant expansion. Before that, foam machines in a bag dispatch the chemical in the center and bottom of the bag. Frequently, an operator will place the bag on a table and spread the chemical manually to disperse it through the bag, so that the bag fits in a limited space, such as between a packed object and a box wall. This not only takes time, but is detrimental to the final condition of the pad, as the foam does not spread until it expands considerably. Compress expanded foam removes gas bubbles
and causes the foam to become denser, which changes the density and protective characteristics designed in the foam pad. Since the pads of the present invention are immediately ready for use as they emerge from the apparatus, they are less expanded and more flexible and can be wrapped in a conformed manner around objects to be packaged, keeping them safer and providing more protection. Since the dispersion of the foaming composition ends before expansion, the foam grows as planned, and the density is as planned. The flat pads formed in accordance with the invention can be used in multilayer packaging, which is especially useful when packing multiple small items. A pad is placed horizontally and the items are arranged in order on it. A next pad is placed over the items and another layer of items is placed over it, followed by another pad, etc. In this way, multiple layers of articles are ispersed between the pads, which adapt to the shape of the articles to secure them. The pads manufactured according to the invention can also be used to align the iior of a box or container. An item can be placed inside a container and then wrapped to keep it in place
and protect it. If multiple items are placed inside a container, the pad can be linked between the items to hold them in place. The above examples are unique applications for flat pads and can not be carried out practically with foam pads in bag made with previous machines, as the pads emerging from such machines are not flat, but have all the foam located at the bottom of the pads. the bag, as noted previously. The present invention, however, can also provide distinct advantages in the use of traditional bag-foam applications. One of those applications is the packaging of fragile items in shipping boxes. In general, an expanding foam bag is placed at the bottom of the box. The item that will be packed is placed on the expanding pad. Another expanding foam bag is then placed in the box over the article and the box sealed while the foam finishes expanding and hardening. With other foam pads in a bag, all the expanding foam is at the bottom of the bag as it is placed inside the box. Frequently, the packer will spread the foam manually to achieve better coverage and filling. The chemical has already grown considerably by the time it spreads. The action of spreading partially expanded foam compels gas from the
foam, so that, as it finishes growing, the foam does not expand completely. Thus, the foam is denser than it was planned to be, so that its protective qualities have changed. Also, because the foam is denser, more chemicals are required to fill the space. This increases the cost and reduces the quality of the packaging and also increases the shipping costs due to the higher weight of the pads. With the pads of the present invention, all redistribution of the chemical is done before it has grown significantly, so the density is correct and less chemical is required. This saves costs and produces a better quality pad. Another advantage is that, since the foam spreads more evenly through and around the packaged object, it fills the space in the cardboard more easily and consistently. The foam in the present invention does not have to travel along the bag while filling the space. This reduces pressures within the box as the foam expands, because the foam does not have to force its way around the object as it expands. The ventilation of the bag and the complications caused by wrinkles in the film are therefore negligible and the wrinkling of foam caused by insufficient ventilation is practically eliminated. Another area in which the present invention has a
Advantage over existing foam products in bag is in the molding of preformed pads. The mold consists of a box with an internal cavity and a lid. The internal cavity has the shape of the desired pad. This cavity generally has a series of holes through which it is connected to a mixing chamber in the back of the mold, which is connected to a vacuum source. An expanding foam bag is placed inside the mold and the vacuum is applied to help suck the expanding foam bag along and deep into the cavity. As described previously, with traditional bag-foam products, all the foam is at one end of the bag, which means that it is at one end of the mold. The mold lid closes and the expanding foam must move to the other end of the mold as it expands and fills. As the foam expands and makes its way to the opposite end of the mold, internal pressures are created that exert great forces on the mold cover. These forces vary depending on the size and shape of the mold, but a mold cap of average size can present forces in excess of 22.68 kg. (50 pounds). The vacuum remains for most or all of the time it takes for the foam to grow, to help the growing foam fill the deeper parts of the cavity.
As mentioned previously, the foam can be spread manually before placing it in the mold, but, again, this densifies the foam and decreases the performance. With the present invention, the foam is spread before it grows significantly and can be adjusted not only along the length and width of the mold, but also to the depth of the cavity. For example, the thickness in the foam can be modified so that if, for example, the pad should be thicker at the ends than in the middle part, the chemical prior to the expansion can be made thicker at the ends than at the end. medium, through the appropriate design and control of the dispersion device. When the bag is placed in the mold, the chemical already covers the length and width of the cavity, so, significantly, the entire expansion of the foam occurs in the direction of the depth of the cavity. The internal pressures and, therefore, the forces on the lid, are greatly reduced. The example of the extra 50 pounds mentioned above may be in the order of 15 pounds with the present invention. In addition, the vacuum needs to be activated for only a short period of time, perhaps a second, because it is only necessary to help the bag settle completely within the cavity. The pads manufactured by this method are of a density and filling more consistent and, thus, are of a higher quality than
the previous methods. In addition, with prior bag foam systems, the foaming composition is delivered under a considerable degree of pressure directly to the lower seal of the bag. Any spillage through a hole or other weaknesses of the seal will cause the expanding chemical to be spilled out of the film, where it can reach the operator, the machine and the items packed with the pad. However, the bottom seal can be protected in accordance with the present invention by the narrow clutch between the dispersion member 7 and the control roller 40, which isolates the seal 83 from the bottom of the foam composition, as illustrated in FIG. FIGURE 9. In addition, the redistribution of the foam composition prevents the foam from expanding from only one point of the bag, and thus reduces the forces in the longitudinal and transverse seal as the foam expands. Again, with reference to FIGURE 1, according to one embodiment of the invention, the control roller 40, the drive rollers 44, 46 on the shaft 48, the dispersion member 70, the frame 72, the anvil 80 and the transverse sealing and cutting wire 82 (not visible in FIGURE 1) and the motors 42 and 74 comprise a module contained therein that can be removed from the apparatus as a unit and replaced by another identical module or
configured differently. The module includes opposite frame members 22a, 24a having support rods 26 connected therebetween. The module is mounted on the apparatus by fixing the butterfly screw 84 of the module in threaded holes corresponding to the frame members of the apparatus. The modularity of the design means that, in a short time, the module can be replaced by one that uses a different film width or a module, with a dispersion member with a different shape. For example, the dispersion member may have depressions within to shape the foam. A large rolling dispersion member with depressions or other shapes inside can be used to create a foam version of the bubble wrap, a waffle shape, or many others. Instead of a rolling dispersion member, a variety of plow-type devices can be used to shape the foam. FIGURE 14 depicts a dispersion roll 170 with an inconsistent transverse shape along its length. In particular, the roller includes a first end portion 172, an intermediate portion 14 and a second portion 176, all of which are circular cylindrical in shape and have a relatively small diameter. In addition, the roller includes two larger diameter portions 178, one located between the first end portion 172 and the intermediate portion 174 and the other disposed
between the intermediate portion 174 and the second end portion 176. The larger diameter portions 178 are circular cylindrical in shape and have a second diameter greater than the first diameter of the portions 172, 174, 176. When a pad containing a volume of composition Foaming is advanced through the space between the dispersion roll 170 and the control roll 40 (FIGURE 10), the pad (FIGURES 15 and 16) is formed to have three portions 182, 184, 186 of relatively greater thickness , as those formed by the respective portions 172, 174, 176 of smaller diameter of the dispersion roller and two portions 188 of smaller thickness, such as those formed by the larger diameter portions 178 of the dispersion roller. The smaller thickness portions are alternately accommodated with the larger thickness portions. The smaller thickness portions 188 can serve as hinges or fold lines that allow the pad to be folded into a generally U-shaped configuration, as depicted in FIGURE 17. As can be seen, the dispersion member 70 can be a drive roller instead of a free-spin roller. For example, as illustrated in a post-inventive embodiment described in FIGS. 18 and 19, the dispersion roll 70 can be mechanically attached to the drive rollers 44, 46 mounted on the shaft.
48, so that the dispersion member is driven together with the drive rollers and the mechanical connection can be designed in such a way that the peripheral speed of the dispersion member has a predetermined relationship with the peripheral speed of the drive rollers 44, 46 (for example, the same as that of the drive rollers). As shown in FIGURE 19, the conduit members 190 (e.g., belts or "O-rings") or the like can be wound around a portion of the core 192 of each of the drive rollers 44, 46 and around end portions 194. projects of the dispersion roll 70 so that rotation of the drive rollers 44, 46 causes the dispersion roller to rotate as well. The relative diameters of the core portions 192 of the rollers 44, 46 and the end portions 194 of the dispersion roller 70 engaged by the guide members 190 may be selected so that the correct conduction radius is provided to set the peripheral speed of the conductor. dispersion roll in a predetermined ratio to that of the drive rolls (eg, equal to or slightly faster than the drive rolls). The drive dispersion roller can advantageously be on a free-spinning roller for various reasons, including a lower tendency for the film to accumulate in front of the roller.
dispersion. As illustrated in FIGURE 19, the drive roller 44 (and, likewise, the roller 46 not shown) may include a cavity at its end, where the portion of the core 192, the driving member 190 and the portion lie. Also, as shown, the shaft 48 for the drive rollers extends through openings in support brackets 196 mounted on a fixed structure of the apparatus. The support clamps are closely adjacent to the ends of the drive rollers with basins. In light of the above description of certain exemplary embodiments of the invention, it will be appreciated that the present invention allows the expanding foam pads to be produced with controlled placement of the foam within the polymer film. Such controlled placement is achieved through the control of the position, speed of movement and operation of the foam dispenser 50, 150, control of the position of the dispersion member 70 and control of the film conduit 40, 44, 46. With respect to the foam dispenser, the position of the dispenser can be controlled as described above, but, additionally or alternatively, the dispenser can be controlled depending on whether it is
dispatching or not while the film is advancing and / or while the dispatcher is in motion. For example, the dispenser may be moved and / or the film may be advancing while the dispenser is alternately turned on to deliver foam and off to stop foam dispensing, thereby creating discrete spaced foam regions. The speed of movement of the dispenser may also vary while the dispenser is in its "on" state dispensing foam. With respect to film driving, the film advance speed may vary while the dispenser is "on" to help control the distribution of the foaming composition. Thus, the invention allows considerable versatility through control over various primary variables that affect foam placement. Just as an example of the versatility afforded by the invention, a pad can be produced with foam distributed in a generally C-shaped extended configuration to facilitate molding the pad in a mold with a C-shaped mold cavity, wherein the two "legs" of the contiguous and C-shaped portions of the upper right part of the extended C-shape between the legs are relatively thick and the intermediate portion of the upper right part is relatively thin. In such a case, it is desirable that the foam be distributed in the
pad before molding, so that there is no more foam composition where thick portions will form and less foam composition where thin portions will form. Accordingly, the following procedure can be used to produce the desired pad: 1) For starters, the dispersion member 70 is closed (as in FIGURE 9), the dispenser 50, 150 is positioned at a point towards a longitudinal edge of the film and the film is driven by a predetermined distance (eg, 5.08 cm (2 inches)) while the dispenser is "off". This provides extra film at the bottom of the pad to create enough space for the foam to expand. 2) The dispenser is "turned on" and the dispenser moves to the opposite longitudinal edge by a predetermined distance (eg, 10.16 cm (4 inches)) and then stops. The film is not driven during this movement of the dispatcher. This creates the lower leg of the C shape. 3) The dispenser remains "on" and the film is driven a predetermined distance (eg, 15.24 cm (6 inches)) at a maximum speed of 80%. This low speed allows more foam to be placed on the pad in this place. The dispersion member is moved to a position that spreads the foam to
an approximate width to the width of the molded pad that will be produced. 4) Through the middle of the upper right C-shape, the molded part has a thinner cross-section. The dispenser remains "on" and the film conduction speed is increased to 90%, so that relatively less foam is dispensed in the intermediate portion. The space between the dispersion member and the control roller widens, so as not to spread the foam so much, since the molded part is thinner, as well as less deep in the intermediate portion on the right. This occurs for a predetermined distance (eg, 45.72 cm (18 inches)) of film travel. 5) The film driving speed is reduced to 80% and the dispersion roller is closed sufficiently to spread the foam across the width of the molded part for the upper thick section, similar to step 3 mentioned above. 6) Then, the film conduction stops and the dispenser (which is still "on") moves towards the first longitudinal edge by a predetermined distance (eg, 10.16 cm (4 inches)), similar to step 2 described above and the dispatcher stops. This creates the upper leg in the form of C. 7) The dispersion member opens completely,
the film is driven by a predetermined distance (for example, a few inches) and then cut. The pad is placed in the mold. The above example is only one of a virtually unlimited variety of processes that can be employed in accordance with the invention to manufacture pads of many different configurations. With the ability to turn the dispenser on and off while the dispenser and / or the film are displaced (whose capacity is not used in the previous example), more complex shapes can still be created. The degree of control over the placement of the foam is made possible by the invention, it not only allows the shape of the pad and its properties to be controlled precisely, but can also facilitate other advantages. For example, it is possible to eliminate or reduce the need to seal the film portions by controlling the placement of the foam so that, even when fully expanded, the foam remains between the film portions without escaping. Therefore, the longitudinal and / or transverse seals can potentially be omitted, thus simplifying the apparatus and process. Many modifications and other embodiments of the inventions set forth herein will come to the mind of one skilled in the art to which these inventions pertain, with the benefit of the teachings.
presented in the previous descriptions and the attached drawings. Accordingly, it will be understood that the inventions are not limited to the specific embodiments described and that other embodiments are intended to be added within the scope of the appended claims. Although specific terms are used herein, they are used only in a generic and descriptive sense and not for limiting purposes.